June 20, 2017

In Quillette Hrishikesh Joshi and Jonny Anomaly* ask Are Liberals Dying Out? Since the piece has been shared a fair amount (judging by my Twitter timeline), I thought I should respond to why I don’t think that is a major concern. Let me jump to their last paragraph:

Nevertheless, despite cultural trends, the best available evidence suggests that political ideology is heritable, and that people with liberal personality traits currently have far fewer children than conservatives. If this trend continues, it is possible that the reproductive choices people are making today will influence the political climate of future generations. Over the long run, conservatives could end up winning the ideological contest with fertility rather than arguments.

First, I don’t think the title reflects the modest contentions of the piece. I beseech the editors of Quillette to not engage in the titular hyperbole so common in the mainstream media!

I agree that political orientation seems heritable. That is clear in books like Born That Way. But heritability expresses itself in an environmental context. If you had a totalitarian government most of the phenotypic variation would disappear. Yes, there would be dissidents, but they’d be freaks. Most humans would conform (no, I don’t think the citizens of Soviet Russia were genetic freaks unable to grasp freedom like Howard Roark). The correlation between religiosity and fertility varies by society as well. The more secular the society, the bigger the gap (though last I checked this was not true in China). In a totally conservative future heritable variation for liberalism could just reemerge.

Second, political orientation exists on a relative plane. If one imagines it as some specific thing, or disposition, one can imagine that in the future the liberal-conservative spectrum would exist, but just be shifted. Quantitative genetics has shown that selection can move the mean many standard deviations. I don’t think this is a strong objection to their overall point, but it gets at the fact that we view liberal-conservative tendencies along a distribution (1980s liberal commentator Jeff Greenfield was widely known for making disparaging comments about gays i the prime of his career; that did not destroy his career as a liberal pundit at that time). Perhaps liberal have already won in an age when most conservatives understand and accept that gay marriage is here to stay.

Third, some of the variation is not heritable. It’s random. In fact around half of it within the population. Some people may just be liberal for stochastic reasons. You aren’t going to get rid of this with selection.

Perhaps most essential in terms of theory: frequency dependence. The dynamics of human interaction and decision making are such that the frequency of liberals declining might have an impact on their fitness. To give a weird example, perhaps an economically post-Malthusian society needs a certain number of sub-replacement liberals who engage in particularly productive work to maintain itself. If society slouched rapidly back toward Malthusianism perhaps everyone would just trudge along at replacement.

The big picture problem is assuming constant directional selection and exhaustion of heritable variation is all well and good when you are selecting for wax-seed oil, but human societies are non-linear systems which are subject to big shocks. They aren’t controlled agricultural genetic experiments.

Finally, let me use an analogous case to make an empirical objection. Many people tell me that the future will be religious due to the same dynamics above. This despite the century long trend toward secularization (parenthetical, God is Back was an ill-timed books, as the United States was shifting toward secularization at that time).

But I want to go back further. France was the first nation to start the demographic transition. In the early 19th century the secular elite was worried about the fertility of devout Roman Catholics, in particular the Poles who were arriving. The secular future they envisioned was threatened. It’s been nearly 200 years since these worries, and in those 200 years France has become more and more secular.

My point with this illustration is that if your theory can not predict the past, it can’t predict the future. At least not robustly. Liberal people will always be with us. So will shy people. And atheists too. They may wax and wane, but human variation persists. On the evolutionary genetic level I think frequency dependent dynamics are such that the fait, in the medium term, of low fitness traits is generally to become oddballs, not extinct. And once they are odd they may become fortunes favorites….

The issue with intelligence is that it’s a highly polygenic trait for which measurement is not always trivial. You need really large sample sizes. It’s about ten times less tractable than height as a quantitative trait. There are still many arguments about its genetic nature (though a majority position that it’s not rare variants of large effect seems to be emerging).

But all in good time.

Science is divided into many different fiefdoms, and people don’t always talk to each other. For example I know a fair number of population genomicists, and I know behavior geneticists who utilize quantitative genomic methods. The two are distinct and disparate groups. But the logic of cheap sequencing and big data is impacting both fields.

Unfortunately when you talk to population genomicists many are not familiar much with psychology, let alone psychometrics. When it comes to the behavior geneticists many come out of psychology backgrounds, so they are not conversant in aspects of genetic theory which harbor no utility for their tasks at hand. This leads to all sorts of problems, especially when journalists go to get comments from researchers who are really opining out of domain.

Some writers, such as Carl Zimmer, are very punctilious about the details. Getting things right. But we have to be cautious, because many journalists prefer a truth-themed story to the truth retold in a story format. And, some journalists are basically propagandists.

Over the next five years you will see many “gene and IQ” studies come out, with progressively greater and greater power. Read the write-ups in The New York Times, Science, and Nature. But to my many readers with technical skills this is what you should really do:

pull down the data.

re-analyze it.

My plain words are this: do not trust, and always verify.

I’m a big fan of people educating themselves on topics which they have opinions on (see: population genetics). If intelligence is of some interest to you, you should read some things. Arthur Jensen’s classic The g Factor: The Science of Mental Ability can be quite spendy (though used copies less so). But Stuart Ritchie’s Intelligence: All That Matters and Richard Haier’s The Neuroscience of Intelligence are both good, and cheaper and shorter. They hit all the basics which educated people should know if they want to talk about the topic of intelligence in an analytical way.

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April 8, 2017

Love to see a post about which human traits worth caring about are notable for having little or no hereditary component. It is all good and well to know what we cannot change, but it makes more sense to focus personally and as a parent on those things that aren’t genetically preordained.

This is a common sentiment I’ve seen. If you haven’t read The Nurture Assumption, please do so. I’d say a substantial reason I think that The Blank Slate is a good book is that Steven Pinker promoted Judith Rich Harris’ work.

With that out of the way: the implication in the comment above is that hereditary traits are the ones you have least control over, so you should focus on the non-hereditary traits. To some extent there is truth in this. Micronutrients are important. You don’t want to turn you children into cretins.

But a major problem with the idea that we can impact environmental impacts on characteristics is that on many traits we don’t know what those environmental impacts are. You can take a behavior genetic model and come to the following conclusion: within the population 50% of the variation is due to genes, 40% of the variation is due to non-shared environment, and 10% of the variation is due to shared environment (parents). We don’t really usually know what the non-shared environment means. It might be just developmental noise. It might be epistatic genetic effects. Or, in relation to behavior, it might be peer group, as Judith Rich Harris asserts.

We just don’t know. What that means is that the hereditary components are what you have legitimate effective control over through mate choice. And shared environment. These two combined are not nothing. And of course there is the impact of nation or community on the environmental in which propensities are expressed.

Addendum: The non-shared environmental variance was once explained to me as a “noise” factor. Just to give you a sense of how well we understand it.

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December 18, 2012

Over at National Geographic David Dobbs of Neuron Culture has an eminently readable and engrossing piece up, Restless Genes. I have never really read about ‘allele surfing’ on the wave of demographic expansion in the way that Dobbs’ rendered it. I certainly wouldn’t have been able to produce that sort of spare but informative prose.

On Twitter there was some concern about the focus on DRD4. The issue is a general one in much of behavioral genomics, and I’m not too interested in rehashing the point. But the broader question of heritability of behavior remains. It seems to me that we have some ‘natural experiments’ now. For the past 50 years there have been a series of cross-cultural adoptions from Asia to North America and Europe. If human behavior variation across and within populations is substantially heritable than this might be a good place to start. Rather than focusing on genes, we need to focus on heritability first.

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October 7, 2012

In The New York Times David P. Barash writes about how parasites might influence our behavior. This should not be too shocking an idea to readers of this weblog, I’ve blogged about Toxoplasma gondii before, on which there has been a raft of publications over the past 10 years or so. My main issue is that like much of behavior genomics I wonder about the possibility of any terminus and conclusion to this line of inquiry (as opposed to being fodder for high publicity publications indefinitely). For any given personality trait we know that a small proportion (on the order of 10 percent) of the predicted variation within the population is due to variation in family environment (i.e., the impact of parent-specific choices). Of the remaining fraction it is about evenly split between genetic effects (i.e., the genes you inherit from your parents, and the consequent dispositions) and “other/non-shared environmental effects.”

This last is really just a residual; we don’t know what’s going on within the model. In The Nurture Assumption Judith Rich Harris posited that much of the remaining environmental component was peer effects. But there are ...

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September 12, 2012

The thread below on the possibility of pedophilia being a biologically mediated tendency rapidly degenerated, to no one’s surprise. As I didn’t have the time to engage in strict moderation I had to close it. And I don’t want to reopen that particular topic. Rather, I want to focus on the issue of psychopathy exhibiting some genetic disposition.

I want to assert immediately that I’m not positing that you’re born a psychopath like you’re born with red hair. Rather, psychopathy is a set of traits whose upstream causes can be both genetic and non-genetic. In fact some cases of psychopathic behavior seems to be rooted in extreme social and psychological deprivation (e.g., orphanages in underdeveloped countries). Interestingly, this may be a case where the environmental input reshapes the developing brain, so that even though the individual may lack a genetic predisposition toward a particular psychology, they may now be biological oriented toward all the traits associated with psychopathy because of the nature of their neurological development.

Going to the model where some people exhibit a genetic disposition toward psychopathy, there are two dichotomous models I’d like to outline. First, there is a model where psychopathy is a deviation from the ...

“There was nothing significant in the frontal lobes or temporal lobes,” says Cantor. “It turned out the differences weren’t in the grey matter. The differences were in the white matter.”

“The white matter” is the shorthand term for groupings of myelinated axons and glial cells that transmit signals throughout the gray matter that composes the cerebrum. Think of the gray matter like the houses on a specific electricity grid and the white matter like the cabling connecting those houses to the grid.

“There doesn’t seem to be a pedophilia center in the brain,” says Cantor. “Instead, there’s either not enough of this cabling, not the correct kind of cabling, or it’s wiring the wrong areas together, so instead of the brain evoking protective or parental instincts when these people see children, it’s instead evoking sexual instincts. There’s almost literally ...

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August 28, 2012

Trends in Genetics has a review article, The genetics of politics: discovery, challenges, and progress. The main reason I point to these sorts of papers isn’t that I think they’re revolutionary. Usually they aren’t. Rather, the public domain has totally forgotten about this domain of study. Most of the informed and high-toned discussion presumes that almost everything of worthy note is socially constructed. If not, then the counterpoint is a crude caricature of genetic determinism which is refutable in a blink of the eye. It’s as if someone was commissioned to paint R. Daneel Olivaw, and ended up using crayon to sketch out the Frankenstein monster.

For example, in sex differences the public debate veers between evolutionary psychological Leave It To Beaver, pre-scientific cultural traditionalism, and de facto Blank Slatism. On the one hand you have to deal with people who use “scare quotes” around the “highly speculative” “hypothesis” that males have a greater tendency toward inter-personal physical aggression than females (including in the comments of this blog, so spare with lectures about how this is a marginal perspective; I’m pretty sure I talk to people about behavior genetics a lot more than you do, though if not I’d ...

A meta-analysis of twin, family and adoption studies was conducted to estimate the magnitude of genetic and environmental influences on impulsivity. The best fitting model for 41 key studies (58 independent samples from 14 month old infants to adults; N=27,147) included equal proportions of variance due to genetic (0.50) and non-shared environmental (0.50) influences, with genetic effects being both additive (0.38) and non-additive (0.12). Shared environmental effects were unimportant in explaining individual differences in impulsivity. Age, sex, and study design (twin vs. adoption) were all significant moderators of the magnitude of genetic and environmental influences on impulsivity. The relative contribution of genetic effects (broad sense heritability) and unique environmental effects were also found to be important throughout development from childhood to adulthood. Total genetic effects were found to be important for all ages, but appeared to be strongest in children. Analyses also demonstrated that genetic effects appeared to be stronger in males than in females. Method of assessment (laboratory tasks vs. questionnaires), however, was not a ...

A meta-analysis of twin, family and adoption studies was conducted to estimate the magnitude of genetic and environmental influences on impulsivity. The best fitting model for 41 key studies (58 independent samples from 14 month old infants to adults; N=27,147) included equal proportions of variance due to genetic (0.50) and non-shared environmental (0.50) influences, with genetic effects being both additive (0.38) and non-additive (0.12). Shared environmental effects were unimportant in explaining individual differences in impulsivity. Age, sex, and study design (twin vs. adoption) were all significant moderators of the magnitude of genetic and environmental influences on impulsivity. The relative contribution of genetic effects (broad sense heritability) and unique environmental effects were also found to be important throughout development from childhood to adulthood. Total genetic effects were found to be important for all ages, but appeared to be strongest in children. Analyses also demonstrated that genetic effects appeared to be stronger in males than in females. Method of assessment (laboratory tasks vs. questionnaires), however, was not a ...

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August 3, 2012

Virginia Hughes has an important post up at The Last Word on Nothing, What Americans Don’t Get About the Brain’s Critical Period. In it she reiterates just how stupid the “Baby Einstein” culture is. The post is important to me specifically because I have a baby who I would like nudge in the direction of Einstein, but not by spending money on toys which exist mostly to salve the vanity and conscience of adults around her. With all that said, Hughes emphasizes that the key is to focus on children at the other end of the environment spectrum from my awesome one.

July 25, 2012

Most of these stolen children were entrusted to the care of Catholics loyal to the regime. The aim behind this was to rid an entire people of the “Marxist gene,” at least according to the theories of Antonio Vallejo-Nájera, the national psychiatrist of Francoist Spain, that were widespread at the time.

More accurately it should be Marxist meme. But it brings up the question of looking into the correlation between the traits of biological parents and their long-lost children.

Jessica Schairer has so much in common with her boss, Chris Faulkner, that a visitor to the day care center they run might get them confused.

They are both friendly white women from modest Midwestern backgrounds who left for college with conventional hopes of marriage, motherhood and career. They both have children in elementary school. They pass their days in similar ways: juggling toddlers, coaching teachers and swapping small secrets that mark them as friends. They even got tattoos together. Though Ms. Faulkner, as the boss, earns more money, the difference is a gap, not a chasm.

But a friendship that evokes parity by day becomes a study of inequality at night and a testament to the way family structure deepens class divides. Ms. Faulkner is married and living on two paychecks, while Ms. Schairer is raising her children by herself. That gives the Faulkner family a profound advantage in income and nurturing time, and makes their children statistically more likely to finish college, find good jobs and form stable marriages.

The story is set up ...

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June 27, 2012

As a father the content of my conversations with friends and acquaintances has changed somewhat. Whereas in my offline life discussions of behavior genetics rarely came up, now they loom large implicitly and explicitly. Though the vast majority of people I interact with have graduate degrees or are pursuing graduate degrees in the life sciences almost none of them are aware of the magnitude of the heritability of most bio-behavioral traits.

For those of you who forgot, heritability is a population wide statistic which assesses the proportion of variation in the population you can attribute to heritable genetic variation. So if heritability is 1.0 all of the variation is due genetic variation; offspring are just a linear combination of their parents. If heritability is ~0.0, then there’s basically no correlation between parents and offspring. Though, as I said, heritability is a population-wide statistic, it can be informative on an individual level. For example, the heritabiilty of height is ~0.90 in the Western world. To give you a sense of the expected height of the offspring of two individuals, just take the average (in sex-controlled standard deviation units) and shift it back toward the mean by 10%. There is going to be ...

As a father the content of my conversations with friends and acquaintances has changed somewhat. Whereas in my offline life discussions of behavior genetics rarely came up, now they loom large implicitly and explicitly. Though the vast majority of people I interact with have graduate degrees or are pursuing graduate degrees in the life sciences almost none of them are aware of the magnitude of the heritability of most bio-behavioral traits.

For those of you who forgot, heritability is a population wide statistic which assesses the proportion of variation in the population you can attribute to heritable genetic variation. So if heritability is 1.0 all of the variation is due genetic variation; offspring are just a linear combination of their parents. If heritability is ~0.0, then there’s basically no correlation between parents and offspring. Though, as I said, heritability is a population-wide statistic, it can be informative on an individual level. For example, the heritabiilty of height is ~0.90 in the Western world. To give you a sense of the expected height of the offspring of two individuals, just take the average (in sex-controlled standard deviation units) and shift it back toward the mean by 10%. There is going to be ...

The American culture promotes personal responsibility, the dignity of work, the value of education, the merit of service, devotion to a purpose greater than self, and, at the foundation, the pre-eminence of the family.

The power of these values is evidenced by a Brookings Institution study that Senator Rick Santorum brought to my attention. For those who graduate from high school, get a full-time job, and marry before they have their first child, the probability that they will be poor is 2%. But, if those things are absent, 76% will be poor. Culture matters.

I’ve been ragging on the cultural Left on this weblog recently because of the delusions that those of this bent simply won’t let go of in the quest for utopian egalitarianism. But one aspect of the American cultural and political scene is that Left and Right often operate with similar presuppositions, only weighting the emphasis differently. While the cultural Left puts the focus on nearly infinite possibilities of individual self-actualization, the cultural Right has backed itself into a corner of individual moral perfectionism which borders ...

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May 17, 2012

What I do, as a historian, is take something apparently simple and make it more complicated. I wonder about how your curves, e.g., would be applied in real life. *Specific* couples, *particular* children–individuals, cases, persons, context.

I’m asking things like:

-What would your hypothetical psychopathic lovebirds do with that information?

Comfort is referring to this figure I generated, which shows the potential distribution of outcomes for two individuals who tend toward more psychopathy than the general population. It seems to me that this question is easily answered if simply replace “psychopathy” with “odds for heart disease.” Endophenotypes aren’t magical, they’re just sometimes hard to characterize. But once you get a good grip on them you can make standard quantitative genetic predictions. One of the points I wasn’t clear about in the chart is that I assume that the “trait” being measured is the tendency toward psychopathy as measured by a paper & pencil test in one’s youth. This does not entail that an individual in fact behaves like a psychopath. Rather, it simply implies that they’re odds of behaving like a psychopath as an adult ...

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May 15, 2012

A few days ago Nathaniel Comfort pointed me to this post, Genetic determinism round-up. If you are curious go read Comfort’s whole post. I honestly didn’t enjoy it very much, I think I got what he was saying, but there were all sorts of circumlocutions around the overall message. But I agree one one thing in particular: an emphasis on concrete and specific genes for traits is a motif in science journalism that can be very frustrating, and often misleading. Nevertheless, that’s not the only story. I believe our current culture greatly underestimates the power of genetics in shaping broader social patterns.

How can these be reconciled? Do not genes and genetics go together? The resolution is a simple one: when you speak of 1,000 genes, you speak of no genes. You can’t list 1,000 genes in prose, even if you know them. But using standard quantitative and behavior genetic means one can apportion variation in the population of a trait to variation in genes. 1,000 genes added together can be of great effect. The newest findings in genomics are reinforcing assertions of non-trivial heritability of many complex traits, though rendering problematic attributing that heritability to a specific set ...

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May 9, 2012

I stopped reading much in the area of personality and behavior genetics a few years back. The main reason is I had a really hard time believing there were very good quantitative measures of many of the traits. A secondary issue, though probably nearly as important, is that some friends were making it clear that they strongly suspected that a lot of the studies in the area of behavior genomics were “underpowered” in a statistical sense. These two issues gnawed at me to the point where I pretty much threw my hands up in the air. Mind you, I accept that personality is substantially heritable. But just because something is heritable does not mean that it is obvious that you’ll be able to detect “the gene” implicated in the variation of the trait. I accepted decades of findings in behavior genetics. But it didn’t seem like we were going anywhere beyond it.

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